Explosives have many useful industrial applications including surface hardening of austenitic manganese alloy steels, surface deposition coating, welding of metallic components, compression molding of components from powders and granular media, and disposal of unwanted explosive or toxic materials.
The prior art reflects many attempts to contain the explosion process for the suppression of noise, shock and noxious polluting explosion products.
Hampel U.S. Pat. No. 5,419,862 discloses a large explosion chamber in which an explosive work piece is introduced in through an air lock into a vacuum chamber where it is detonated, and after detonation the explosion products are allowed to escape into the atmosphere. The chamber is mechanically secured by anchor rods to a foundation.
Gambarov, et al. U.S. Pat. No. 4,100,783 discloses a cylindrical containment vessel, split along its diameter for separation, and openable for the insertion of large work pieces such as railway frogs, stone crusher wear parts and the like. After insertion of a work piece and explosive charge, the chamber is closed and locked and the explosive detonated by a built-in detonating device. The explosion combustion products are allowed to exhaust to the atmosphere through an air valve.
Deribas U.S. Pat. No. 4,085,883 and Minin U.S. Pat. No. 4,081,982 disclose spherical containment vessels with a bottom opening through which a work piece incorporating an explosive is introduced through an elevator means, and continuous feed wire electrodes are used to make contact with an electrically initiated detonator when the work piece is in place. The latter patent also discloses means for introducing an internal liquid spray after the explosion for the purpose of neutralizing toxic by-products of the explosion.
Smirnov, et al. U.S. Pat. No. 4,079,612 discloses a roughly hemispherical containment vessel mounted on a concrete foundation with a shock-absorbing work table for supporting the work piece and explosive material, which are detonated through electric ignition wires leading through openings in the containment vessel to the outside.
A different approach is disclosed by Paton, et al. U.S. Pat. No. 3,910,084 in which multiple closed-end pipes are disposed radially around a central column in which the explosion is initiated, with the shock waves dampened by internal baffles within the tubes. Access is gained to the chamber through a removable top cover plate.
Klein, et al. U.S. Pat. No. 3,611,766 discloses a vertical explosion chamber incorporating a cushioned work table for supporting the work piece and explosive charge, and an internal shock-mounted mechanical dampening means consisting of a steel grate for absorbing the explosive pressure waves. Klein U.S. Pat. No. 3,464,249 discloses a similar containment vessel, in this case spherical, with a bottom covering of loose granular material such as sand which supports the work piece and explosive charge. The explosion products are discharged through a vertical pipe containing a noise silencer, and the entire assembly is supported by shock absorbing means in a reinforced brick or concrete pit for the further suppression of shock and noise.
All of the above prior art devices represent improvements over the methods first used for explosion hardening of manganese steel rail components which involved placing the explosive-covered work piece in an open field, or at the bottom of an open pit such an abandoned gravel pit, and setting off the explosion in the open air with resultant noise, dust, disturbance and contamination of the environment. In addition, the uncontrolled use of explosives required great amounts of space, posed substantial danger to equipment and personnel, and had the undesirable effect of demolishing the ignition leads, the work piece support surface, and everything else within the immediate vicinity of the explosion.
It is therefore the principal object of the present invention to provide an improved method and apparatus for containing, controlling and suppressing the effects of explosive detonations used for industrial purposes. The purpose of the invention is to provide a containment device which can contain and suppress each explosion so that it poses no hazard to surrounding plant and equipment, or to the environment.
A further object is to provide such a method and apparatus which permits rapid and convenient charging and removal of work pieces, thereby achieving much higher rates of production than have been possible using prior art devices and techniques. A related object is to provide an explosive containment vessel which can be constructed inexpensively of common materials using conventional welding techniques but which is sturdy enough to withstand months and years of continuous use without deterioration. A related object is to provide such a device in which inexpensive consumable materials, such as silica sand and pea gravel, are used as damping and shock absorbing agents, rather than complex and expensive internal springs, metal grates, and the like.
Another object is to provide an explosion containment chamber which is readily opened from one end to allow charging and removal of work pieces by conventional means such as a forklift truck, and to allow easy entrance and exit by maintenance personnel. A further object is to provide quick and efficient removal of gaseous explosion by-products after detonation so that maintenance personnel can immediately enter the chamber to remove the treated work piece and put another in place for the next operation.
Still another object is to provide an internal ignition system in which the electrical leads for the detonation initiation system are protected from blast effect and are reusable for a great number of explosion cycles, rather than being destroyed and having to be replaced after each cycle.
Another principal object of the invention is to provide a means of quickly removing and treating the gaseous explosion by-products by passing them through a scrubber system, so that operating personnel can re-enter the chamber immediately while the scrubber continues to process the products of the previous explosion as a new work piece and explosive charge are being readied. Also, it is an object of the scrubber system to further dampen and suppress shock and noise from each detonation by virtue of the extended travel path of the explosion products as they pass through the scrubber.
Finally, a particularly important object of the invention is to provide a simple and inexpensive means for absorbing the unused energy of the explosion, for instantaneously reducing temperatures and pressures within the chamber, while at the same time suppressing dust and particulate matter in the explosion by-products.